Therapeutic proteins provide unique and critical treatments for many human diseases and conditions However, if a protein product cannot be stabilized adequately, its benefit to human health will never be realized. Proteins are highly susceptible to the formation of non-native aggregates and precipitates, which can cause adverse reactions in patients, ranging from immune response to anaphylactic shock and even death. Unfortunately, the mechanisms that control aggregation of therapeutic proteins are poorly understood. We have developed a tightly interwoven set of experiments, theories, and molecular level simulations to address our central hypothesis that the kinetics and thermodynamics of aggregation of therapeutic proteins are controlled by three main factors: conformational stability, colloidal stability, and interactions with interfaces. Each of these factors can be manipulated by changing solution conditions, protein structure, or both. To test our central hypothesis, we will manipulate protein conformational stability, protein-protein intermolecular interactions, and protein-surface interactions by employing innovative, state-of-the-art experimental methods. We have chosen a large set of model proteins in order to encompass a broad range of protein structural classes, molecular weights, and functionalities. These experiments, and their interpretation, will be complemented by innovative computer simulations and theoretical frameworks aimed at understanding the mechanisms that control protein aggregation at a molecular level. The Biotechnology Research Partnership team will be led by Prof. Ted Randolph, director of the Center for Pharmaceutical Biotechnology at the University of Colorado. Key scientific personnel on the team include Prof. Kristi Anseth (U. Colorado) an expert in biological applications of polymers, Prof. John Carpenter (U. Colorado Health Sciences Center), an expert in formulation of therapeutic proteins, Prof. Carol Hall, a leader in the field of computer simulations of protein aggregation, Prof. Kristi Kiick (U. Delaware), an expert in production of artificial proteins, Prof. Christopher Roberts (U. Delaware), an expert in modeling an analysis of protein aggregation, and Prof. Daniel Schwartz, a leader in studying protein behavior at interfaces. Relevance: To improve the safety of protein-based drugs, the problem of aggregation must be solved. The proposed research will discover how aggregation occurs, and develop strategies to prevent it.